| 摘要 |
In a method for manufacturing a camshaft for an internal combustion engine a metal tubular element is expanded within a mould with the aid of a fluid at high pressure fed into the tubular element and with a simultaneous axial compression of the tubular element. The cams of the camshaft are formed in subsequent steps, starting from intermediate cams and ending with end cams. In a first step of the method, the intermediate cams are formed in a first mould. In a subsequent step, the end cams are formed within auxiliary moulds which surround, only throughout a predetermined length, end portions of the tubular element which project from the mould which surrounds the already formed intermediate cams. In this subsequent step, the tubular element is compressed axially by axially displacing two clamp members, which grip and surround completely, throughout a predetermined length, the end portions of the tubular element which project outwardly from the auxiliary moulds. |
| 主权项 |
1. A method for manufacturing a camshaft for an internal combustion engine, wherein a metal tubular element is expanded within a mould with the aid of a fluid at high pressure fed into the tubular element and with a simultaneous axial compression of the tubular element,
wherein cams of the camshaft are formed in subsequent steps, starting from intermediate cams of the camshaft and ending with end cams of the camshaft, wherein:
in a first step of the method, the intermediate cams are formed within a first mould which surrounds only an intermediate portion of the tubular element, said first mould having a cavity with portions having a shape and dimensions corresponding to those of the intermediate cams to be formed and a remaining part of said cavity having a cylindrical shape and a diameter corresponding to an outer diameter of said tubular element, said tubular element being arranged within said first mould with end portions of the tubular element projecting from said first mould,during said first step of the method, fluid at high pressure is fed into the tubular element, while the tubular element is simultaneously compressed axially by displacing two clamp members axially towards each other, which clamp members grip and completely surround, throughout a predetermined length, the end portions of the tubular element which project outwardly from said first mould,in a subsequent step of the method, the end cams are formed within auxiliary moulds which surround, throughout a predetermined length, the end portions of the tubular element which project outwardly from a second mould which surrounds the already formed intermediate cams,said auxiliary moulds have cavities with portions having a shape and dimensions corresponding to those of the end cams to be formed and a remaining part of said cavities of said auxiliary moulds having a cylindrical shape and a diameter corresponding to the outer diameter of said tubular element,said auxiliary moulds are initially located axially spaced apart from opposite ends of the second mould which surrounds the intermediate cams which have been already formed, said tubular element end portions projecting beyond said auxiliary moulds,during said subsequent step of the method, fluid at high pressure is fed into the tubular element, while the tubular element is simultaneously compressed axially by displacing the two clamp members axially towards each other, which clamp members grip and completely surround, throughout a predetermined length, the end portions of the tubular element which project outwardly from said auxiliary moulds,during said subsequent step of the method, said clamp members are pushed axially until they come in contact against said auxiliary moulds and then they are kept to be pushed axially until moving said auxiliary moulds in contact against the second mould which surrounds the already formed intermediate cams,so as to form the end cams of the camshaft, while the cavities for forming the end cams are brought to a final axial position, in which said cavity portions of said auxiliary moulds for forming the end cams are located at a proper axial distance with respect to the intermediate cams which have been formed already. |
